Effect of π-spacers on the photovoltaic properties of D–π–A based organic dyes

Abstract

• Triphenylamine containing different conjugated spacers were synthesized for photovoltaic performance. • Broad absorption is observed by introducing thiophene group in triphenylamine moiety. • The obtained HOMO and LUMO values were sufficient for efficient electron injection as well as regeneration of oxidized dye. • Triphenylamine having benzene linker shows high efficiency than other dyes. Three new triphenylamine based D–π–π–A (TPC, TSC and TOC) dyes with different π-spacers have been synthesized and analysed their significance on the photophysical properties and photovoltaic applications. The synthesized dyes were characterized by NMR, mass, melting point, absorbance and electrochemical measurements. In these dyes, triphenylamine moiety was utilized as electron donor and cyanoacetic acid acts as an electron acceptor. By keeping phenyl acetonitrile as one π-spacer and another π-spacer is varied by benzene/furan/thiophene group and their consequences on the photophysical, electrochemical and photovoltaic properties were analysed. Photovoltaic parameter such as short circuit current density ( J SC ) and open circuit voltage ( V OC ) is found to be significantly varied by changing the π-spacer. The maximum absorption was observed for TSC with thiophene linker which results in high J SC value than TPC and TOC. However, a high V OC of TPC results in better photovoltaic performance of 3.52% among other dyes. The outcome from the photophysical and photovoltaic measurements implies that the phenyl and thiophene spacer yields higher power conversion efficiency when compared to the furan bridged dye. The observed results will provide basic information for future designing of sensitizers with different π-spacers for photovoltaic applications.